At the Palomarin Field Station we have been monitoring birds and their environment since 1966. Since the beginning of our study, the area adjacent to the mist nets and banding station has undergone drastic habitat change, resulting in shifts in the local bird community. Tracking the changes in the habitat alongside the changes in bird populations at Palomarin can inform bird conservation as we learn more about what environmental factors are most important for certain species to thrive. Here, you can explore the habitat changes and bird community changes we have recorded through our long-term data collection.

How has the habitat changed?

During the 15 years before the field station was established, the land around Palomarin was partially cultivated for agricultural use and hosted many buildings. Since its inclusion in the nascent Point Reyes National Seashore in 1965, the land has not been disturbed significantly and habitat succession has gradually taken place.

Overlooking the Palomarin study area in the 1970s. Photo by Point Blue
Overlooking the Palomarin study area in 2006. Notice the dark patches of Douglas fir trees on the hillside and in the flats. Photo by Point Blue

In the earlier years of our study, the landscape at the field station was comprised of two distinct habitat types: the mist-netting and banding site was largely forested while the area adjacent, where much of our nest searching takes place, was dominated by short, open coastal scrub.

The vegetation across the study area has since grown in size and structure and has become a complex mix of mature scrub with tall coyote brush, poison oak, California blackberry, and a young, dense Douglas fir forest. We have documented the change in the average height of these firs over time, as well as an increase in the number of trees in the study area, and the height of shrub species like coyote brush.

Mean height (and standard error) of Douglas fir trees at Palomarin, 1983–2018.

How has the breeding bird community changed?

A Wrentit peering out from its nest. Photo by Dennis Jongsomjit

Biologists at Palomarin survey the breeding bird community through mist netting and bird banding, as well as searching for nests and mapping the boundaries of breeding bird territories.

Nearly every day during the spring and summer, biologists collect data on the movements and behaviors of breeding birds to create territory maps representing that season’s breeding bird activity. The number of territories provides us with a measure of how many breeding individuals of each species are present in the bird community.

As the vegetation has changed, the breeding bird community has also changed a lot since the early 1980s, especially the addition of more species associated with mature forest.

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Tracking the changing number and composition of breeding bird territories at Palomarin, 1982–2018. Because the breeding bird community is so diverse, this figure is limited to the 15 species that have ever ranked in the top 5 for the number of territories in one year.



Extra attention is paid to four primary focal species, which are also given unique combinations of colored leg bands so we can more easily identify individuals in the field: Song Sparrows, Nuttall’s White-crowned Sparrows, Wrentits, and Wilson’s Warblers. The number of Song Sparrow and Nuttall’s White-crowned Sparrow territories have declined, while Wilson’s Warblers and Wrentits have greatly increased.

Number of territories for our 4 primary focal species each year, 1982–2018.

Why is tracking habitat change important for bird conservation?

At Palomarin, we witnessed the open coastal scrub residents that once flourished here (such as White-crowned Sparrows) fade from the study area while more forest and mixed scrub species (such as Wilson’s Warblers and Swainson’s Thrushes) moved in. Witnessing and studying this shift has answered some questions, and incited further study to determine what it is that certain species need to survive and thrive. Studying how birds within a community respond differently to changes in their environment provides us with information to help inform and guide conservation efforts. Land management and restoration projects can benefit from this type of research by understanding how best to create an environment that supports a more resilient bird community.

How did we collect these data?

During the breeding season (March-July), three interns spend their days stealthily tracking birds to map the boundaries of the territory each one calls home, as well as to find their nests and determine how successful each nest attempt is. The interns are trained in how to identify and follow birds by both sound and sight, as well as how to find and safely monitor their nests. A bird that sings in the same area day after day is considered a territorial individual. After months of recording the movements and territorial behavior of individual birds, we compile all of this data into territory maps for each species.

A nest-searching intern observing and recording bird behavior and movement. Photo by Point Blue
A territory map for Wrentits in 2018. Each circle represents the territorial area occupied by a breeding pair. Image by Point Blue

Each summer, we collect vegetation data at 8 fixed points throughout the study area. The data helps describe the habitat succession as well as the proliferation and growth of the Douglas fir trees. At each of the 8 points, we record the size (height and width) and species of all woody plants along four 10-meter transects.

Meet our biologists!

Visitors can drop in at Palomarin to join our intern and staff biologists, learn how we collect this data, and hopefully see a bird in the hand! More information on visiting and scheduling groups.

More information